Nowadays, the primary raw material for the transparent conductive layer of the array substrate and the colorfilm substrate in the production of liquid crystal displays is indiumtin oxide (ITO), which is a metal oxide. ITO can provide high optical transparency and relatively good conductivity. However, it exhibits conductivity lower than metals such as gold and silver. Thus, there are some limitations when it is used in the fields of touch screens, displays, plasma displays, etc. Additionally, the abrasion resistance of the ITO film is relatively poor, and at the same time the cost of indium, which is the main component of ITO, is relative high, therefore, the use of optical film having better properties, such as graphene-metal composite electrode, has become a trend.
The monolayer graphene is a two-dimensional structure of a closely packed atomic monolayer. The specific electronic configuration thereof determines its excellent electrical property. In the monolayer graphene, carbon atoms periodically arrange in the graphite plane in the form of six-membered ring. Each carbon atom binds three adjacent carbon atoms via a bonds. The three hybridization orbitals, i.e. S, Px and Py, form an sp2 hybrid orbital, which imparts the graphene extremely high mechanical properties. The remaining π electrons in the Pz orbital form a π orbital in the direction perpendicular to the plane. The π electrons can move in the plane of the graphene crystal, which allows the graphene to possess a good conductivity. Furthermore, investigations indicate that transparency of a graphene electrode would not be affected when it combines in a grid style with metal having small size.
Therefore, it is possible to develop a new alternative conductive material for indium tin oxide (ITO) for the production of the conductive layer used in liquid crystal displays, by utilizing the superior conductivity and transparency of the graphene.